1. Field of the Invention
The present invention relates in general to radio communication systems and components. More particularly the invention is directed to antenna elements and antenna arrays for radio communication systems.
2. Description of the Prior Art and Related Background Information
Modern wireless antenna implementations generally include a plurality of radiating elements that may be arranged to provide a desired radiated (and received) signal beam width and azimuth scan angle. For a common three sector cellular coverage implementation each antenna will have a 65 degree (deg) azimuthal coverage area. It is desirable to achieve a near uniform beam pattern that exhibits a minimum variation over the desired azimuthal degrees of coverage. In modern applications, it is also necessary to provide a consistent beam width over a wide frequency bandwidth.
In addition in modern cellular applications a number of antenna elements may be configured in an array to provide beam control by phase control of the beam, for example to provide beam tilt or beam steering. Providing an antenna array with a number of antenna elements in a typical cellular installation can create problems related to antenna weight and size. Also, cost is very important in such applications. Accordingly, providing the desired antenna performance is made more difficult by the need to maintain low cost, weight and size.
Consequently, there is a need to provide an improved antenna structure with desired beam uniformity over a desired coverage area. Furthermore, it is desirable to provide such an antenna in a relatively compact and low cost construction suitable for use in antenna arrays.